Neuroplasticity and memory formation in major depressive disorder: An imaging genetics perspective on serotonin and BDNF

Abstract

A vast number of imaging studies have demonstrated the impact of serotonin (5-HT) and brain-derived neurotrophic factor (BDNF) on emotion and memory-related networks in the context of Major Depressive Disorder (MDD). Underlying molecular mechanisms that affect the functionality of these networks have been examined in detail in animals and corroborate imaging findings. The crucial role of 5-HT and BDNF signaling in the context of MDD is reflected in the etiologic models of MDD such as the monoamine or neuroplasticity hypothesis as well as in pharmacological models of antidepressant response. While antidepressant drug treatment has been primarily linked to the modulation of emotion-related networks, cognitive behavioral therapy has been implicated in a top-down control of limbic structures. Initially, a simple lack of monoamines or BDNF has been proposed as causal factor of MDD etiology. However, recent findings suggest a much more complex neurobiology emphasizing epistatic and epigenetic mechanisms responsible for structural and functional changes observed in emotion and memory-related brain regions of healthy subjects and MDD patients. In this review, which focuses on neuroimaging studies in the context of MDD, the authors will provide a comprehensive overview of these networks as well as on the specific role of 5-HT and BDNF in their development and function.

Photobiomodulation for Alzheimer’s Disease: Has the Light Dawned?

“…If it can be conclusively shown that tPBM stimulates neuroplasticity and synaptogenesis in humans as well as mice, then this opens the door to a wide range of clinical applications [126]. Impaired or aberrant neuroplasticity has been implicated in a wide range of brain disorders such as Alzheimer's [127], psychiatric disorders [128], stroke [129], TBI [130], and addiction [131].…”

Major depressive disorder: mechanism-based prescribing for personalized medicine

“…53 , 54 Structural and/or functional alterations have been identified in brain regions involved in emotional processing as well as cognitive control, learning, and/or memory formation. 51 , 55 …”

Neuroimaging genomic studies in major depressive disorder: A systematic review

“…10 Considerable genetic-neuroimaging literature indicates that there are significant associations between genetic variants and structural and/or functional neuroimaging alterations in MDD, implying new neuroimaging phenotypes to MDD. [11][12][13][14][15] Although no specific pathophysiological mechanism of MDD had been reliably identified, genetic-neuroimaging studies reveal that genetic variants are implicated in some common hypotheses of the pathogenesis of MDD, 4 such as monoamine-deficiency hypothesis, hypothalamic-pituitary-cortisol hypothesis, and altered glutamatergic neurotransmission. Monoaminergic genes and BDNF genes have repeatedly been studied, which were associated with morphological and functional alterations of emotionrelated brain areas and made it susceptible to MDD.…”

“…Monoaminergic genes and BDNF genes have repeatedly been studied, which were associated with morphological and functional alterations of emotionrelated brain areas and made it susceptible to MDD. 11,13 Hence, numerous genetic-neuroimaging studies have attempted to explore the pathophysiological mechanisms of MDD via analyzing the associations between genetic variants and structural and/or functional neuroimaging abnormalities. However, previous review only focused on the role of 5-HT and BDNF genes in structural and functional alterations in emotion-and memory-related brain areas and failed to provide a comprehensive overview of all available genetic variants expected to play a pathophysiological role in MDD.…”

“…However, previous review only focused on the role of 5-HT and BDNF genes in structural and functional alterations in emotion-and memory-related brain areas and failed to provide a comprehensive overview of all available genetic variants expected to play a pathophysiological role in MDD. 13 In addition, different neuroimaging techniques or genetic variants may be potential confounding factors that would result in heterogeneity of genetics-neuroimaging studies.…”